The present invention relates generally to semiconductor fabrication and more specifically to bump processing for semiconductor device fabrication.
To electrically communicate between semiconductor device circuitry mounted on a chip carrier and from outside the chip, bonding pads that electrically communicate with the semiconductor device circuitry are exposed through a passivation layer over a wafer. xe2x80x9cBumpsxe2x80x9d may then be formed over the bonding pads with wires, for example, attached to the bumps that permit electrical communication between the semiconductor device circuitry and outside the chip.
Mushroom structure plating is used to obtain the desired final bump height without any change from a design point, i.e. without forming wider openings exposing the under bump metal (UBM) upon which the bump is deposited.
U.S. Pat. No. 5,665,639 to Seppala et al. describes a process for manufacturing a bump electrode using a rapid thermal anneal (RTA) that minimizes the intermixing of materials between a bump and a bonding pad.
U.S. Pat. No. 6,051,450 to Ohsawa et al. describes a method of manufacturing a lead frame whereby metal films to constitute bumps are formed on a metal base by electrolytic plating and then a circuit wiring including inner leads is formed by electrolytic plating with a metal so that the inner leads are connected to the respective metal films.
U.S. Pat. No. 5,904,156 to Advocate, Jr. et al. describes a process for wet chemically stripping dry, thick film photoresists in semiconductor applications.
U.S. Pat. No. 5,882,957 to Lin describes a ball grid array (BGA) packaging method for an integrated circuit (IC).
U.S. Pat. No. 5,633,535 to Chao et al. describes an apparatus having standoff spacing pedestals supporting a device above a substrate during solder reflow and bonding.
Accordingly, it is an object of the present invention to provide an improved method of forming mushroom bumping plating structures.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a structure having an exposed first conductive structure is provided. A first photoresist layer is formed over the structure and the exposed first conductive structure. A second capping photoresist layer is formed over the first photoresist layer. The first and second photoresist layers being comprised of different photoresist materials. The first and second photoresist layers are patterned to form an opening through the first and second photoresist layers and over the first conductive structure. The second capping photoresist layer prevents excessive formation of first photoresist layer residue during processing. A second conductive structure is formed within the opening. The first and second patterned photoresist layers are stripped. The second conductive structure is reflowed to form the bump structure.